低信噪比下低复杂度的OFDM信号带宽盲估计方法

Bandwidth blind estimation scheme of OFDM signals with low complexity at low SNR

针对低信噪比多径信道下传统的正交频分复用(OFDM)信号带宽盲估计方法估计精度低且计算量较大的问题,提出了一种低复杂度的OFDM信号带宽盲估计方法.首先利用修正的周期图求平均(Welch)法得到功率谱,再对其进行最小二乘多项式拟合得到平滑的功率谱,然后通过对功率谱曲线进行求导提取出斜率最大点和最小点的位置进而估计带宽,最后多次循环求统计平均得到信号带宽的精确估计.通过理论分析,确定了OFDM信号带宽盲估计方法的步骤,并在多径信道下进行了仿真试验.仿真结果表明,该方法在信噪比为0 dB时能够达到98.9%的正确估计率,并且该方法与传统方法相比,带宽估计精度更高,计算复杂度更低.

To solve the problem of poor performance with large amount of calculation work for traditional orthogonal frequency division multiplexing（OFDM） bandwidth blind estimation scheme at low signal to noise ratio（SNR） over multi-path channel, an OFDM bandwidth blind estimation strategy with low complexity was proposed. The Welch method was adopted to estimate the power spectrum of OFDM signals. The smooth spectrum was obtained by least square polynomial fitting. The derivation of smooth spectrum was calculated to extract the maximum and minimum positions. The statistical average value was consi- dered as the final bandwidth blind estimation value by repeating many times. The steps of OFDM band- width blind estimation scheme were determined by theol7 analysis, and the simulation experiments were conducted under multi-path channel. The simulation results show that the correct rate of the bandwidth estimate scheme is 98.9% for SNR of 0 dB with multi-path channel. Compared with traditional method, the proposed method has better estimation performance with smaller calculation work at the conditions of low SNR and multi-path channel.